Multiple-part curable resins (e.g., epoxides and dental restorative resins) are commonly dispensed and mixed using a multiple-barreled syringe equipped with an exit nozzle containing a static mixing element. The materials contained in the syringe are dispensed and mixed by depressing the syringe plunger, thereby forcing the resin components from the syringe barrels into the static mixing element (where the resin parts are intermixed with one another) and out the exit nozzle.
Similar apparatuses have been known in which fluids to be mixed have been dispensed by double barreled syringe or caulking gun type dispensers (see e.g. U.S. Pat. Nos. 3,309,814, 4,041,463, and 4,538,920). Dispensing devices of this general type, as is well known in the art, are useful in the application of a variety of pasty or highly viscous products such as adhesives, joint filler agents, foams, sealants, molding compounds etc. Such products typically consist of two or more components which are stored separately and mixed at the time of use in order to start a chemical reaction between them, usually causing a solidification or hardening of the resultant mass.
U.S. Pat. No. 4,767,026, for instance, describes a dispensing device and disposable mixer combination in which the dispenser stores the fluids separately and delivers them to an orifice in which the fluids are maintained in separation to the point of interface between the orifice. Other examples of mixing devices are described, for instance, in U.S. Pat. Nos. 5,566,860, 5,474,540, 5,071,040, 4,995,540, 4,846,373, 4,735,616, 4,676,657, 4,631,055, 4,359,049, 4,044,758, 4,040,420, 3,806,097 and 3,223,083.
On a separate subject, Applicant has previously described a system for resurfacing joint surfaces that includes the step of delivering a curable two-part biomaterial by minimally invasive means. See, for instance, U.S. Pat. No. 5,556,429 and PCT Application Nos. PCT/US97/00457 and PCT/US, the disclosures of each of which are incorporated herein by reference.
When used in such a minimally invasive method, e.g., to resurface or repair ajoint in situ, most if not all of the above-described commercial syringe assemblies suffer from several shortcomings, including the fact that the devices tend to be too long for convenient, ergonomic use. Generally, the length of the device is a function of the overall length needed to fully mixed the components. While not typically a concern when used for industrial or other applications, the overall length of conventional devices renders them difficult to use, e.g., awkward to position, manipulate and control, in the course of surgical procedures that require precise control and are performed by minimally invasive techniques under fiberoptic visualization.
Much of the overall length of a conventional device is required solely to provide a mixing path that is of sufficient length to thoroughly mix the components. The length of the mixing path is generally determined so as to provide sufficient mixing, on the one hand, and the ability to deliver the material before it sets, on the other. Rather than be concerned with overall length, the mixing efficiency of such devices can actually be improved by providing either a longer mixing path and/or improved geometries of the mixing elements themselves.
In the course of using such commercial devices for minimally invasive surgical procedures, Applicants have found that it would be highly desirably to have a device that provides several features that are not typically provided by the above described devices. Such features would include, for instance, automated and/or single-handed control and operation, as well as the ability to control the device in sufficient proximity to the surgery site to facilitate ergonomic control while preventing premature curing of the biomaterial. What is needed, therefore, is a device that can be used to mix and deliver multiple part curable systems in a manner that addresses the unique and demanding surgical needs set forth above.